Abstract:

In clayey soil, soil particles generally possess negative ions, and form an electronic field nearby the particles. With the function of electronic attraction force and Brown (thermal) movement force, electronic attraction force is much stronger nearby the surface of soil particles, ions and polar molecules are closely attracted to particles surface that forms a close layer around the particle. Outside this layer, the electronic attraction force decreases as the distance increase from the surface of the particle, and they form a dissipative layer. Ions in the dissipative layer and negative ions in the soil particles surface form diffuse double layer. Based on diffuse double layer theory, when the distance between two clay planets is known, the seepage force can calculate using the ion concentration at the middle plane between two planets. In the same way, the ion concentration at the middle plane between two planets is known, the distance between two planets can be calculated. The soil water characteristics of densely compacted Gaomiaozi bentonite has been obtained using osmotic and vapor phase techniques under free swelling conditions. At the same time, the volume change behavior of Gaomiaozi bentonite under unconfined conditions has been calculated using diffuse double layer theory. Comparison between calculated results and test data has also made. Results show that there is a good consistence between calculated results and testing records for the volume change of densely compacted Gaomiaozi bentonite under low suction.

Key words: diffuse double layer theory, Gaomiaozi bentonite, osmotic technique, volume change behavior